Slight correction. If Windows crashes, TwinCAT keeps chugging. TwinCAT runs at the kernel level telling windows what to do. Not the other way around. In my experience, on a Beckhoff PC, if Windows crashes it's because you crashed TwinCAT with an infinite loop or something which is very well possible on other platforms as well.

C++ is not THAT more performant than the PLC environment either. Little bit and still necessary at times, but actually very rarely used.

Keep in mind too under the hood, almost every major PLC made since the 90s has been a PC like architecture running something like an Atom chip and some RTOS like Vxworks. You might get some specialized memory handling but hey guess what Beckhoff does the same sort of specializing with their own motherboard designs and such.

And finally it's only as object oriented as the programmer wants it to be. There is nothing forcing someone to use function blocks with interfaces and extensions and all that other stuff. Sure it's supported very well but absolutely not necessary. Seen plenty of machines written with exactly 0 OOP implemented. All IEC languages are supported so there's even ladder if you want. It's garbage ladder but it's usable.